SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f527533298c60d0b6974d1876f62e100a7e3f7abcc7972779268237517d23af1' 
  AND token = 'UNuIE+VSNXZQwwhG3OAU/XvZbX/7v2s85odBUAQ2TpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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