SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31a22c6ec28272edd2052c32be793db2778ff95695547f72dec8482d9013bbe4' 
  AND token = 'xivIUSMEBay/Ep94nEaGq9EexPdyQ1pCvCYpW4UfNAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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