SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5336c2c88b40a827b144797b47dd09978835265204faebce9246f8155884707' 
  AND token = '05VwYDA2FCYRPTCNzJspKrn172+JBt/CtVPy7rvVwiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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