SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6146f690945be7fbffaed6b2753732199508a53b2997194c38668838f0a1a812' 
  AND token = 'nF+jwQWYjNUz7kzF1wQMhS9/nHYkQ4OTfdofka3/jso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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