SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd83863f76306a789cbbb6284b54562f5d5b3495c9457336b1789f398da960ef6' 
  AND token = 'fWo96l/juX3/rA0CuSAi2gnDy1VbfxxnAeGjHpBX0m8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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