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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15fbc3fb2eae19516486f14ac16d813fd4f8454ec9823ad0fe4f8ea6054cda01' 
  AND token = 'Kpdw0TnQht2Qkkuc1QHMb1+JikHuiwNJOtcVwKUaEQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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