SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5ab1fd3eed848467e1a8f786012d58f7f31ae0f86af354202f646d815700fea' 
  AND token = 'pIoyCaV4gPJwWC/aCuOhwRR5V+d29m+nv8giCpnj1RI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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