SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2124fd3ac1adc480f0f2dee1f9bb58b5ec635dc687233aa71e351aefaf274827' 
  AND token = 'c9bVDmMR36eyzHFXxhFe8v8POHO2uKPk36g5PLquKHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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