SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87e1346515d5163143c67f29d355f3b314859f13bb19207749375f2c71fbbe8e' 
  AND token = '7jDOznds+j3NO8NoyaLJUXCvEaYzj1BVvXxcYLpi5wI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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