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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff86bf67e06d4874f4ace1e0f6f7d21ee053fb7d17a949dc9e7d96afe0f1ee56' 
  AND token = 'afjRihKO3JDVMD4ETOR2fUAzvKYhTSoBWxQY00pcO/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}