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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '52b91c929f02516d063e5212b59bd9d21fab435f0a8c5d618691922d35516fc2' 
  AND token = 'wrFxBmA+j/Y3+/OusT4s0ZcJ6uNvzLQ1As2e3RB5zXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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