SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74bceeaaa54277026a60d8c942f9448622a7818069fcd6290d0612038dbbace8' 
  AND token = 'jgfBVbSFrO80jDRlz8qVECMlaWtkrXRbPi4LSfrXwL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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