SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64063bd193bd16e6430e23deb746125e792ffe56a15d1f9fee7caaaa40492c84' 
  AND token = 'EPIntSpwaLnz6aI8NEl0B4rUfIvUa93nnBTfeBjtS0M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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