SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ff68580b20e6d8ebdae4995588f223bac328d5f1cbe61e19a868e8617c344ee' 
  AND token = 'MRXfgejEr9hMiJ5qrYQ7ZbDQ4Bj5Lses0Vf+E4qPz1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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