SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b075d1c6200f711432f811fc9451e7a21b653299681bdf5f5784301de63d15a' 
  AND token = 'Y6eLBObkxElL8uyzHowd1s6x4UW/Hb/1Gq4t7Ro+E3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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