SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3caf04616bc509ae854197955d4d34117a91daeda1c423785001fffcaf6ea17e' 
  AND token = 'U2jDZyFnMZL4xBSUBB94kY/3vqJ9JaXrWgSoSvfxg6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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