SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1f450a35a67bb87f73d37d483c46788209f753781970dca19da3e0393bfcb31' 
  AND token = 'Py4spSglhJYYmtWsG5QuSBErWBMLqXzYR873NwxsaIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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