SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c7d1048f7aa3246791f3ecf710ed0ab75738e4d0bc924846e14d04800b92644' 
  AND token = 'e+eImmbR+r/y87fGBpmM0ifaySEcjZ/TIBPj/Bpfehk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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