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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d684952809b85432b44074b1eff6521d80c48d3dfe4352d0b6f8ab5668c4f7' 
  AND token = 'sm44ZzTcwsPcN2ZRjlpZ83RhFhNjO3JGPkDT9YXqNbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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