SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8799699334f858575cfb705d44b90322a4dfaeadd24fc2640d36f092850e43e' 
  AND token = 'qKYywGMasauBOR2zKQ8B+KCi+P9lyU/w7/MwsTZYyk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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