SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be7c8f4f91b8852f2c16e0b3e7c0f82bd25a03d9805bb35168256adeaf4870b1' 
  AND token = 'SAQsAUtJI1mitVgvp+sQ76KfNgPjVbHk46/h8Px+uJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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