SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3f69c70f2c10fe2fbc7deede41c7dbe9ba410c8698bc963821487f358ff181' 
  AND token = 'iPPxPfTRDUuXzHeSLCgvbgJbv9WCLlDk9ZzEPLFdFM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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