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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e88f1c2058fdfe96cd2ddf652efb1103c1c9a3c44e7ae71d94492b1abae814d8' 
  AND token = '6WWZ/Fr+dTdhYp5b6gMe/7idiyb5KzkhX3lrZNj5wbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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