SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e3fe0a9b379cb42260a601ac41c7b67603df59de6d16668cc2065e7d5f0e467' 
  AND token = 'x/EobuuEJ3R3p8aY9Iz5pfqvbXYGpDJsl4is5HCahf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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