SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7940834402c456e7d5040bb8a05e50d640dda650fdc98bb1bf9cfe0b5de8360a' 
  AND token = 'FTFGBT6eMhnrC5Etcx4V+dcKUPtcbw+X4hBDS4Hkwck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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