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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '815ee112175a0773d46c7be86843ab1934491363f0d7f01deecfb21778872d54' 
  AND token = '8HVrmfigDcT3ivVb+cXgaUgLP5ybfCxL/b/qVdO/suY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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