SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b835197f08a2fa43ccc0cb57cf3dd0a175f5cf653c3939335efb44224136a75d' 
  AND token = 'OX/oPZPb0NNEC+HiYHO1OGwluyGVt14GLt6wwaziJwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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