SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f3bbd0e3d97122e02727a7a0d9748efde910330f44bbfa7dedc4f47f144a96' 
  AND token = 'T8UMqj9Y9RCw3ZZrlzzc5R0XBTxWbekU+rGwmUJdI34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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