SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ffb0b46dd51c57300de606f46a4521d2af2bf00a2478884a149b0572dfe8771' 
  AND token = 'vLh35h6lHHHuObCLhtlT2hJwze/VJdLiKeIExgZmiGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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