SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d4e223246008a064db94c52e2fd95c40a46a8f3337df4d3931e73c1ed62fdf5' 
  AND token = 'PlaDnoiLJvBlqVzlzQGiwiHTV5IcuXvZpGUFXzhcWBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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