SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90f5102d0790f9ed86bd97bbaf0a348d4ee4a64c8cc5dc2dff2d8565d381d568' 
  AND token = 'SxzxNCDt2a6wiXbbeHBigMH71/CYsM0EjwDAXfIyiGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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