SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e8f736cb778221d52fd1febe00249ef1d5d0978cfad99cdf42439b855a5e799' 
  AND token = 'rCaqyN/0wXSaS71tyjYtO3su/SCxSNhldmUB0UFB6to=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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