SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b87b59d8dc5ac9ae7d327506e9a7a6610baad761f56fe18befc9d25a30f124bb' 
  AND token = 'id6Rsjs1E/spDMZLYmMipb3ARrAHX1tIkRnFC/awgVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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