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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3f7e9d621ce1ebb543f179b04b28845821e73b62e111ceafc2fbe3246d93b75' 
  AND token = 'uT6UqqfIzj604f59eb2YVNPuFbBXIBDkeVDLgQSA2u4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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