SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4122710a3cf21c4df3dfb50c2500c826f94336477794decbe67f35a3f7aaadf2' 
  AND token = 'QgBjOM2TyGePvOu4wCTXr9QTdkGFmsup+5p3CWKGwVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}