SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9864d0bd1bc387163610250d7b313112cd903e39ce13e1bc2778a076c7c0dfd' 
  AND token = '/uUVqYMEUnuZYDVhA+VdULY8SaIae3Mk1lSIOcoW+cc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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