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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c548ec93e7bb3c7f2bfc845ba20f8b75893dae2df397d21d4b2f39e5cff0bf94' 
  AND token = 'PRLzOExeKt6qfVMDlpjkZJwjmFSIZm8lWEHacY9n8MQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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