SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '268e3b1a738407962ca5888cf0e50b72ea1ac562ee58881dda99ab9686d3c2ab' 
  AND token = 'hi/VIT/XTsMKh+BzBsRfI8Fv7F//kzOL1vvmg5pCxQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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