SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3b8382791ad44f84454b030c1c7799aaa51c59ab92d69be70eaf39850bf4ffc' 
  AND token = 'muv87RjwYH5CAqNH7lBc3V4vVSJ41qQbboRhPKdrJhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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