SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '674a1b50762e3410d3ef9d57cb2237274f08db32e115767b514493783de93a1c' 
  AND token = 'g3tfVx0++u8vnErrMtCQzVduoHSfvzqVwLiiXOmiMHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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