SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '034f6af827f796f63306e623b385cc6977322c47292a3325a138d384d82cd926' 
  AND token = 'gamlKUhiokd+RunXa4rpoh5sAWj1/ZIwBzXZMg8WYzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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