SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b829ccf15dc43302ee8941a75d35fe66da2279f2b1b29e07886334f53971349c' 
  AND token = 'HJlV6SfLih872BSAJaRrK6uTzIohJq5Cq3v4k0hUoQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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