SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c82815614f82fa1c6eb902f9eccc1078bb917d421331167ec9ad0e64d5357fa1' 
  AND token = 'urwh4G/rcaxUJYSCQZ+P6JgiTiKjEsvW5tEHXyEt/aA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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