SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c63bc2dc17372311a2ef327aee7f532201e557ca0519011918fa151389780606' 
  AND token = 'FBDKqUo00Bzn11aeiiJLkUTPp/OCpqhiBs1Xtym84nk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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