SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f8a85347f4c6f59012cb31300bfd24906f44fc6ab6739e5a7efab3850243b6b' 
  AND token = '4AgWNlvdaY0A4kdaCCMF/pkUzxdE0xU1yLUcNlF15DM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}