SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50ddf8da15174d41046a105f6caaa925b251f989eeafd1b131115bb9c0ce5052' 
  AND token = 'An0gFA+RbjpRahLO0y4rm9sTpHefgqm5hzb2Grz/KG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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