SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14f673e83ed06b9f81b2cb588decbee26b786618c22859cb7c84d722a440e8e2' 
  AND token = '6LSMRbqJs7s3ofKhZbKtKHRlcaGzxARlnoAMl+lbykA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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