SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dfc68e74aa0c36258311649536a457140a3fcbf9768b3fe76830b23c6baa477' 
  AND token = 'T6nmlTgWzSz79kDqSetQOvTQTyp0K7s4JdmzAnk2yeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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