SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '935c9435b71dad6015c26bdd3f9d0b1452d176c0c8e4d381657d7d50f2546e67' 
  AND token = 'T1TcxeyEpfY8fxtgxcNCK5TxYGJQXwJSJ+vq8uwvo+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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