SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4ef68a3847a9170169f063d8af8372cdb5990add576212579f8320dc8a3dfeb' 
  AND token = 'LwwqizWg8+tJLY02xG4z+Yj8wmd8TgcTGakQ0qtV+VQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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