SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39c55e13c481710930132818c07e312d8b087acb01302874fba9dab5f0d1a9b9' 
  AND token = 'bIzgQ2m0ljsAW23K3Xji7LrNw5t/aB+Rz+sqwyQYp1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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