SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3f47bc0299ec5693b23859b636f1e4f8f481f4b6c37e5b5c670b795c1251d75' 
  AND token = 'HBmY5Zufb1HLwmXrVyKaH3Np7Tfoq2UY0HjeyLVvagY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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