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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd394588b62afc8e61846d45043f7ff2d9834bf85d93463cb9dc3651472ce9d69' 
  AND token = 'QMR18uydH1fyc5HJ9wLNUk1OeamRzUek5rNSS3rJS6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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