SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a57c06cb753c55cf0d53eb1c57ec318130362d56268037acb76681b768a2f7' 
  AND token = '0dnIK2LQnuoXPguMF+rVeZvNdTAakLHSfkdDbDMxPbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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